Overview of Hypertension

High blood pressure is often called the silent killer, since nearly one third of people that suffer from it have no idea that they have it.

Hypertension is the medical term for high blood pressure. With each beat of the heart, blood is pumped through the arteries, creating a measurable pressure within the blood vessels. At the beginning of the heartbeat, when the ventricles contract to push the blood through the circulatory system, the highest pressure is exerted on the arteries. This is called the systolic pressure. As the ventricles of the heart are filled with blood at the end of the heartbeat, the blood pressure falls to its lowest level, the diastolic pressure. These pressure measurements are taken by an instrument called a sphygmomanometer which is connected to an inflatable bag wrapped around the upper arm. Air is first pumped into the bag until blood flow through the main artery in the arm is interrupted. As the air is slowly released from the bag, the instrument can measure the pressure in the artery as the heart beats and blood pumps through it once again (systolic), followed by the pressure of the relaxed artery (diastolic).

Blood pressure is not constant from heartbeat to heartbeat, because the heart rate regularly changes in response to physical activity or other cues from the external environment. Average blood pressure varies throughout the day, and can also change temporarily in response to nutritional factors, illness, and stress. Hypertension refers to the condition of having consistently high blood pressure that exceeds normal, healthy levels. Currently, doctors consider healthy blood pressure to have readings of 120 systolic and 80 diastolic. This might be spoken as “120 over 80” in talking with your doctor. Researchers have found that blood pressures of 140 over 90 or higher can be damaging if sustained over many years, leading to a great number of medical complications, including stroke, kidney failure, heart attack, and heart failure.

Symptoms of Hypertension

Unless the blood pressure increases very suddenly, people are unlikely to notice it, as hypertension does not have symptoms in and of itself. In fact, approximately one third of people that have hypertension do not realize it until it is measured by a doctor. People with chronic hypertension may gradually develop symptoms as their blood vessels become stressed, however. Untreated hypertension can lead to vision changes, confusion, fatigue, and chest pain. In some extreme cases, patients also have irregular heartbeat or blood in their urine due to the side effects of hypertension. It is important, particularly as people become older, to heed these warning signs, as they may indicate that they are at risk for the dangerous complications that can arise from high blood pressure.

Risk Factors of Hypertension

If hypertension goes untreated, it may cause numerous physical complications.
People with hypertension are at a greater risk for having strokes. A stroke is a loss of brain function due to interruption of blood flow to part of the brain, which can potentially cause permanent physical or mental difficulties. (Please see our article on Stroke for more information.) The stress of the excessive pressure on the blood vessels in the brain may also cause them to break, resulting in a hemorrhagic stroke. As the broken vessels bleed, the tissues awaiting blood downstream can become deprived of blood and oxygen and become irreparably damaged. Even if the vessels do not burst, the increased blood pressure in the brain can result in a condition called hypertensive encephalopathy, an altered mental state due to the abnormally high pressure that can lead to difficulties in thinking, subtle changes in personality, lethargy, and depression. In more extreme cases, the pressure on the brain can also cause a person to experience tremors, seizures, and respiratory problems.

The tiny blood vessels within the eye may also be damaged in patients with chronic hypertension. This condition, also called hypertensive retinopathy, may cause headaches or visual problems due to the thickening or leaking of the blood vessels in the eye.

Hypertension is also one of the most common conditions contributing to both heart attack and heart failure. A heart attack, or myocardial infarction, occurs when the heart’s blood supply is cut off, usually by a blockage in the vascular system. If the hypertension arises from high blood cholesterol or atherosclerosis, the pressure on the walls of the blood vessels can potentially dislodge plaques, which are fatty cholesterol-laden lesions that form within the blood vessels. Although these fatty deposits are relatively rigid, the blood vessel walls are elastic, so the increased blood pressure may stretch them, freeing the plaques into the blood stream.

Whereas a heart attack is caused by the inability of blood to get into the heart, heart failure occurs when the heart is unable to pump sufficient blood through the body. Hypertension increases the force with which the heart has to beat in order to pump blood through the body. Over time, this can weaken the heart muscle significantly.

Hypertension can also put a person at risk for kidney failure, which can, in turn, exacerbate the hypertension by stimulating the production of a kidney protein called renin. Renin is an enzyme that causes a narrowing of the blood vessels (vasoconstriction). This constriction of the blood vessels further increases the blood pressure, entering the body into a dangerous feedback loop that perpetuates hypertension.

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